Refrigerator with energy consumption optimization using adaptive fan delay

ABSTRACT

A method of determining a time delay for turning off an evaporator fan in a refrigerator after a compressor of the refrigerator is turned off includes operating the evaporator fan in the refrigerator for a period of time, operating the compressor of the refrigerator to cool the refrigerator to a predetermined temperature after turning off the evaporator fan, determining a power consumption value for operating the compressor to cool the refrigerator, repeating the previous steps to obtain a plurality of times and a plurality of power consumption values, selecting the time coinciding with a lowest power consumption value, and adapting the refrigerator to use the time as the time delay for turning off the evaporator fan in the refrigerator after the compressor of the refrigerator is turned off.

FIELD OF THE INVENTION

The present invention relates to refrigerators. More particularly, thepresent invention relates to refrigerators which adapt to theirenvironments by adapting fan delay time in a manner that increasesenergy efficiency.

BACKGROUND OF THE INVENTION

Energy efficiency is important to the design of refrigerators.Refrigerator parameters are typically optimized fortesting/certification conditions to provide the best energy consumptionas determined by various energy efficiency tests. However, therefrigeration cycle is affected by the home environment conditions insuch a way that the refrigerator will consume more energy due to controlparameters mismatch between the testing/certification conditions and thehome environment conditions. Thus, there is a parameter detuning effect.The parameters that are affected are related to the time delay betweenthe events of turning off the compressor and turning off the evaporatorfan. The fan time delay, if not optimized, can lead to a drop inefficiency in the refrigeration operation. Once the compressor is offthe time delay that controls the fan will re-circulate the air in thecavities through the evaporator to use its remaining cooling capacity.At some point, the evaporator temperature will be higher than thefreezer and then it will stop cooling and warming up the freezer. Lateron, the compressor will have to apply more energy to reduce theaforementioned temperature delta. Thus all of this will result inadditional energy cost.

Although a thermocouple could potentially be used to avoid such aneffect, introduction of a thermocouple increases cost and designcomplexity as the sensor and wiring would need to be added.

What is needed is a method to find an optimal time delay to turn off theevaporator fan of a refrigerator.

SUMMARY

Therefore, it is a primary object, feature, or advantage of the presentinvention to improve over the state of the art.

It is another object, feature, or advantage of the present invention toprovide a refrigerator which will adapt to its environment and enable itto run as efficiently as possible.

It is a further object, feature, or advantage to provide a method forfinding an optimal time delay to turn off the evaporator fan of arefrigerator.

It is a still further object, feature, or advantage of the presentinvention to provide a refrigerator which operates efficiently bothunder the parameters typically used for testing and certificationconditions as well as within home environments with varying conditions.

Another object, feature, or advantage of the present invention is toprovide a refrigerator which need not use a thermocouple to determine anoptimal time delay to turn off the evaporator fan of the refrigerator.

Yet another object, feature, or advantage of the present invention is toprovide for tighter temperature control.

One or more of these and/or other objects, features, or advantages ofthe present invention will become apparent from the specification andclaims that follow. No single embodiment need exhibit all of theseobjects, features, or advantages as it is contemplated that differentembodiments may have different objects, features, or advantages.

According to one aspect, a method of determining a time delay forturning off an evaporator fan in a refrigerator after a compressor ofthe refrigerator is turned off includes operating the evaporator fan inthe refrigerator for a period of time, operating the compressor of therefrigerator to cool the refrigerator to a predetermined temperatureafter turning off the evaporator fan, determining a power consumptionvalue for operating the compressor to cool the refrigerator, andrepeating these steps to obtain a plurality of times and a plurality ofpower consumption values. The method further includes selecting the timecoinciding with a lowest power consumption value, and adapting therefrigerator to use the time as the time delay for turning off theevaporator fan in the refrigerator after the compressor of therefrigerator is turned off.

According to another aspect, a refrigerator includes a refrigeratorhousing, at least one compartment disposed within the refrigeratorhousing, a compressor, an evaporator, an evaporator fan, and a controlsystem disposed within the refrigerator housing and operativelyconnected to the compressor, the evaporator, and the evaporator fan. Thecontrol system is configured to determine a time to operate theevaporator fan after turning off the compressor to assist in optimizingefficiency of the refrigerator in cooling the at least one compartment.

According to another aspect of the present invention, a method isprovided for determining a time delay for turning off an evaporator fanin a refrigerator operatively connected to a smart grid after acompressor of the refrigerator is turned off using the smart grid. Themethod includes operating the evaporator fan in the refrigerator for aperiod of time, operating the compressor of the refrigerator to cool therefrigerator to a predetermined temperature after turning off theevaporator fan, and then determining a power consumption value, thepower consumption value including power consumed by operating thecompressor to cool the refrigerator, wherein the step of determining thepower consumption value is performed using a power meter associated withthe smart grid. The method further includes communicating the powerconsumption value to a device external to the refrigerator and storingthe power consumption value and the period of time. These steps may berepeated in order to obtain a plurality of times and a plurality ofpower consumption values. The method further includes selecting the timecoinciding with a lowest power consumption value from the plurality oftimes and the plurality of power consumption values. The method furtherincludes communicating the time to the refrigerator through a power gridinterface. The method further includes adapting the refrigerator to usethe time as the time delay for turning off the evaporator fan in therefrigerator after the compressor of the refrigerator is turned off.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 illustrates one example of a system including a refrigerator.

FIG. 2 illustrates one example of a refrigerator.

FIG. 3 is a diagram illustrating timing.

FIG. 4 is a block diagram of a method.

FIG. 5 is a flow chart showing a method.

DETAILED DESCRIPTION

The present invention provides for finding an optimal time delay to turnoff the evaporator fan of a refrigerator. As used herein the term“optimal time delay” is to be understood to convey that a time delayresults in improved energy efficiency or energy conservation under a setof parameters or circumstances. The method includes recording theconsumed power which may be determined from a smart grid wattmeter for anumber of settings of the fan delay. Then a search of the resulting datamay be used to determine what the optimal time delay is for energyconservation.

FIG. 1 illustrates one example of a system 10. The system 10 includes asmart grid control system 12. An electric meter 14 such as the electricmeter associated with a residence is operatively connected to the smartgrid control system 12. An intelligent network controller 16 isoperatively connected to the meter 14. The intelligent networkcontroller 16 may also be operatively connected to the refrigerator 30.Information may be communicated to and from the refrigerator 30 throughpower line networking and/or wirelessly. In addition, a device 20 may beoperatively connected to the smart grid control system 12. The device 20may be used to collect and store information associated with energyusage.

In operation, a system 10 may be used to convey information from thesmart grid control system 12 to the refrigerator 30. The refrigerator 30may be connected to and access power information including from a smartgrid's power meter. Alternatively, the refrigerator 30 may access ameter 18 which is connected to the refrigerator 30. The meter 18 may bepresent within the refrigerator or be external to the refrigerator.

Thus, consumed power information can be provided to the refrigerator ina number of different ways. The consumed power information may beprovided to the refrigerator through the smart grid or through a meterassociated with the refrigerator. The consumed power information maythen be used by the refrigerator in determining the time delay forturning off the evaporator fan after the compressor is turned off.

FIG. 2 illustrates a diagram of a cooling system of a refrigerator 30with a refrigerator housing 44. The cooling system includes anevaporator 42, a compressor 48, and a condenser 40. An evaporator fan 50is positioned at the evaporator and a fan 52 is positioned at thecondenser. A suction line 54 is shown between the compressor 48 andevaporator 42 and a capillary tube 62 and gas dryer 60 are shown betweenthe condenser 40 and the evaporator 42.

As shown in FIG. 2, there is a control system 46 that is operativelyconnected to the compressor 48 and the evaporator fan 50. The controlsystem 46 uses meter information such as the consumed power informationin determining the time delay for turning off the evaporator fan 50after the compressor 48 is turned off. Such information may be in theform of meter information 38 which may come from a meter within therefrigerator 44, a meter within the home, or a meter associated with thesmart grid. An interface 36 is also operatively connected to the controlsystem 46. The interface 36 may be a wired interface or wirelessinterface which allows the control system 46 to communicate with anetwork or a smart grid. Thus, the interface 36 may be a networkinterface or a smart grid interface. An external device 20 may also beoperatively connected to the interface 36 thereby allowing therefrigerator 30 to communicate with an external device 20. The externaldevice 20 may be used to store information and/or process information.

A user input 34 is also operatively connected to the control system 46.The user input 34 may be used by a user to provide input which may beused by the control system 46 to determine the time to operate theevaporator after turning off the compressor. For example, the user input34 may be used by a user to initiate the process of identifying the timecoinciding with the lowest power consumption.

FIG. 3 illustrates a timing diagram for operation of the compressor andthe evaporator fan. A first signal 70 shows operation of the compressor.A second signal 72 shows operation of the evaporator fan. There is afirst time delay 78 between when the compressor turns on and when theevaporator fan turns on. There is a second time delay 80 between whenthe compressor turns off and when the evaporator fan turns off. A line76 shows temperature of the freezer and line 74 shows the temperature ofthe evaporator. As shown in FIG. 3, once the evaporator fan is turnedon, the temperature of the evaporator increases and then increases ahigher rate once the compressor is turned off and at a higher rate yetonce the evaporator fan is turned off. At point 75, heating of thefreezer cavity starts.

FIG. 4 illustrates a diagram showing an algorithm for setting timedelay. Power information 90 is sent to low pass filtering 92 to providefiltered power 94. Integration 96 is then applied. This then allows adetermination of energy as a function of time delay 98 to be determined.A supervisory control 100 may be used in this process. Then optimum setpoint determination 102 occurs resulting in an optimal set-point 104 forthe time delay.

FIG. 5 illustrates one example of a flow diagram. In step 110 anevaporator fan is operated for a period of time. In step 112 acompressor is operated to cool to a predetermined temperature afterturning off the evaporator. In step 114 a power consumption value foroperating the compressor is determined. This step may be performed byusing a power meter associated with the refrigerator. The power metermay be associated with the smart grid, may be onboard the refrigeratoror be external to the refrigerator. In step 116 steps 110, 112, and 114are repeated in order to obtain a plurality of times and a plurality ofconsumption values. Then in step 118 a time coinciding with the lowestpower consumption value is selected. In step 120 the selected time isused as the time delay for turning off the evaporator fan after thecompressor is turned off. The method shown in FIG. 5 may be initiated invarious ways. For example, the method may be initiated after receivingan input from a user at the refrigerator. Thus, for example, a user mayuse a user interface associated with the refrigerator to indicate thatthe method of FIG. 5 should be performed in order to set the time delay.Alternatively, the method may otherwise be performed on demand. In analternative embodiment, the method shown in FIG. 5 may be scheduled. Forexample, the method may be scheduled to be performed at night to avoiddisturbing the user of the refrigerator.

When collecting the power consumption values, the present inventioncontemplates taking into account machine state and variations which mayaffect power consumption values. For example, for proper comparisonbetween power consumption values the defrost heater and the ice makermay both be off. Similarly, sources of variation should be taken intoconsideration or eliminated. Examples may include the amount of foodwithin the refrigerator, the occurrence of door openings, the ambienttemperature, the compressor temperature, and line voltage. Scheduling atnight may reduce or eliminate some of these variations. Alternativelyvariations may be compensated for by the control system. In addition,when collecting the power consumption values differences associated withthe time delay for the evaporation fan may be taken into account.

In addition, the present invention contemplates that the process may beperformed by a control system of the refrigerator. Alternatively,information may be communicated to a device external to the refrigeratorsuch as through a smart grid and the device may be used to storedifferent power consumption values and select a time coinciding with alowest power consumption value. Thus, for example, referring now to FIG.1, an external device 18 may be used to perform calculations or storeinformation. The external device 18 may be a computing device having amachine readable storage medium.

The above described embodiments are for illustrative purposes only anddo not limit the scope of the claimed invention. The invention is onlyto be limited by the claims appended hereto. Therefore, other changesnot mentioned explicitly are intended to be included as part of thescope of the invention. This may include the type of refrigeratorconfiguration, the manner in which the process is performed, the orderin which steps of a method may be performed, whether a power meter isinternal or external to the refrigeration, variations in how the processis initiated, the manner in which sources of variation are compensatedfor or reduced, and other options, variations, and alternatives.

What is claimed is:
 1. A method of determining a time delay for turningoff an evaporator fan in a refrigerator after a compressor of therefrigerator is turned off, the method comprising: (a) operating theevaporator fan in the refrigerator for a period of time; (b) operatingthe compressor of the refrigerator to cool the refrigerator to apredetermined temperature after turning off the evaporator fan; (c)determining a power consumption value, the power consumption valueincluding power consumed by operating the compressor to cool therefrigerator; (d) repeating steps (a)-(c) to obtain a plurality of timesand a plurality of power consumption values; (e) selecting the timecoinciding with a lowest power consumption value; and (f) adapting therefrigerator to use the time as the time delay for turning off theevaporator fan in the refrigerator after the compressor of therefrigerator is turned off.
 2. The method of claim 1 further comprisingreceiving an input from a user at the refrigerator and performing steps(a)-(f) in response to the input.
 3. The method of claim 1 furthercomprising scheduling performance of steps (a)-(f).
 4. The method ofclaim 3 wherein the performance of steps (a)-(f) is scheduled at night.5. The method of claim 1 further comprising communicating each of theplurality of times and each of the plurality of power consumption valuesfrom the refrigerator to a second device.
 6. The method of claim 5wherein the second device being a device external to the refrigerator.7. The method of claim 5 wherein the second device being in operativecommunication with the refrigerator through a smart grid.
 8. The methodof claim 7 wherein the determining the power consumption value isperformed using a power meter associated with the smart grid.
 9. Themethod of claim 1 wherein the determining the power consumption value isperformed using a power meter associated with the refrigerator.
 10. Themethod of claim 1 wherein steps (a)-(f) are performed in alphabeticalorder.
 11. A refrigerator, comprising: a refrigerator housing; at leastone compartment disposed within the refrigerator housing; a compressor;an evaporator; an evaporator fan associated with the evaporator; acontrol system disposed within the refrigerator housing and operativelyconnected to the compressor and the evaporator fan; wherein the controlsystem is configured to determine a time to operate the evaporator fanafter turning off the compressor to assist in optimizing efficiency ofthe refrigerator in cooling the at least one compartment.
 12. Therefrigerator of claim 11 wherein the control system provides for (a)operating the evaporator fan in the refrigerator for a period of time;(b) operating the compressor of the refrigerator to cool therefrigerator to a predetermined temperature after turning off theevaporator fan; (c) determining a power consumption value, the powerconsumption value including power consumed by operating the compressorto cool the refrigerator; (d) repeating steps (a)-(c) to obtain aplurality of times and a plurality of power consumption values; (e)selecting the time coinciding with a lowest power consumption value. 13.The refrigerator of claim 12 wherein the control system being furtherconfigured to use the time coinciding with the lowest power consumptionvalue as the time delay for turning off the evaporator fan in therefrigerator after the compressor of the refrigerator is turned off. 14.The refrigerator of claim 11 further comprising an interface forinterfacing the refrigerator to an external device.
 15. The refrigeratorof claim 14 wherein the interface is a power grid interface.
 16. Therefrigerator of claim 14 wherein the interface is a network interface.17. The refrigerator of claim 11 further comprising a user inputoperatively connected to the control system, and wherein the controlsystem is adapted to determine the time to operate the evaporator afterturning off the compressor in response to input received through theuser input.
 18. The refrigerator of claim 11 further comprising a powermeter operatively connected to the control system.
 19. A method ofdetermining a time delay for turning off an evaporator fan in arefrigerator operatively connected to a smart grid after a compressor ofthe refrigerator is turned off using the smart grid, the methodcomprising: (a) operating the evaporator fan in the refrigerator for aperiod of time; (b) operating the compressor of the refrigerator to coolthe refrigerator to a predetermined temperature after turning off theevaporator fan; (c) determining a power consumption value, the powerconsumption value including power consumed by operating the compressorto cool the refrigerator, wherein the step of determining the powerconsumption value is performed using a power meter associated with thesmart grid; (d) communicating the power consumption value to a deviceexternal to the refrigerator and storing the power consumption value andthe period of time; (e) repeating steps (a)-(d) to obtain a plurality oftimes and a plurality of power consumption values; (f) selecting thetime coinciding with a lowest power consumption value from the pluralityof times and the plurality of power consumption values; (g)communicating the time to the refrigerator through a power gridinterface; and (h) adapting the refrigerator to use the time as the timedelay for turning off the evaporator fan in the refrigerator after thecompressor of the refrigerator is turned off.